2 6 12 20 30... 9900
来源:学生作业帮助网 编辑:作业帮 时间:2024/10/07 00:55:05
1-1/2-1/6-1/12-1/20-.-1/9900=1-1/2-(1/2-1/3)-(1/3-1/4)-(1/4-1/5)-……-(1/99-1/100)=1-1/2-1/2+1/3-1/3+1
3/2-5/6+7/12-9/20+11/30-13/42+…+197/9702-199/9900=(1+1/2)-(1/2+1/3)+(1/3+1/4)-(1/4+1/5)...+(1/98+1/9
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+…+(1/99-1/100)=1-1/100=99/100
通项=(n(n+1)-1)/n(n+1)=1-1/n(n+1)=1-(1/n-1/(n+1))1
6分之1+12分之1+20分之1+30分之1+.+9900分之1=(1/2*1/3)+(1/3*1/4)+...+(1/99*1/100)=1/2-1/3+1/3-1/4+...+1/99-1/100
原式=1-1/2+1-1/6+1-1/12+1-1/20+…………+1-1/9900=99-﹙1/2+1/6+1/12+1/20+……+1/9900﹚=99-﹙1-1/2+1/2-1/3+1/3-1/
1/2+5/6+11/12+19/20+29/30+...+9701/9702+9899/9900=1/2+(1-1/6)+(1-1/12)+(1-1/20)+(1-1/30)+……+(1-1/970
1/20+1/30+1/42+……+1/9900=1/(4×5)+1/(5×6)+1/(6×7)+……+1/(99×100)=(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+……(1/99
这个倒不是很难1/2+5/6+11/12+19/20+...+9898/9900=(1-1/2)+(1-1/6)+(1-1/12)+……+(1-1/9900)=99-(1/(1*2)+1/(2*3)+
原式=1/1*2+1/2*3+……+1/99*100=(1/1-1/2)+(1/2-1/3)+……+(1/99-1/100)=1-1/100=99/100
1/6+1/12+1/20+.+1/9900=1/2*3+1/3*4+1/4*5+...1/99*100=(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+...(1/99-1/100)=1
1/2+1/6+1/12+1/20+...+1/9900=1-1/2+1/2-1/3+1/3-1/4+……+1/99-1/100=1-1/100=99/100
3/2+7/6+13/12+.+9901/9900=1+1/2+1+1/6+1+1/12……+1+1/9900=99+(1-1/2+1/2-1/3+1/3-……+1/99-1/100)=99+(1-1
成本甲=9900/(1+10%)=9000成本乙=9900/(1-10%)=11000成本汇总=9000+11000=20000收入=9900+9900=19800总体:收入-成本=19800-200
(1000-100)/25=40-4=36
=(1-1/2)+(1/2-1/3)+...+(1/99-1/100)=1-1/100=99/100
9901,9902,9903,9904,9905等
=1/2*3+1/3*4+1/4*5+……+1/99*100=1/2-1/3+1/3-1/4+1/4-……-1/99+1/99-1/100=1/2-1/100=49/100
99×100=9900
9900/100×4=396